Abstract
The oxidation of cysteine to cystine was investigated in aqueous thin films generated by the deposition of electrospray ionization (ESI) microdroplets. The confined volume of the thin film promotes the reaction, resulting in up to 80% conversion of cysteine to cystine at a thin film temperature of 40 °C. The pH of the solution is a critical parameter, influencing both the yield and the kinetics of the reaction. Strong reaction acceleration factors in thin film with respect to the bulk were measured.